[Dovecot] postfix pipe to deliver, null_sender.

[Erland Nylend]

Hello,

I just noticed a problem on our servers .. If I send myself a
bounce, like this:

| [en at mailserver ~]$ telnet localhost 25
| Trying 127.0.0.1...
| Connected to localhost.localdomain (127.0.0.1).
| Escape character is '^]'.
| 220 mailserver ESMTP Postfix
| helo foo
| 250 mailserver
| mail from: <>
| 250 2.1.0 Ok
| rcpt to: my at mail.address.tld
| 250 2.1.5 Ok
| data
| 354 End data with <CR><LF>.<CR><LF>
| testing
| .
| 250 2.0.0 Ok: queued as 673072767C
| quit
| 221 2.0.0 Bye
| Connection closed by foreign host.

Then the resulting mail message I get, has this header:

| Return-Path: <MAILER-DAEMON>
| Delivered-To: my at mail.address.tld
| Received: from foo (localhost.localdomain [127.0.0.1])
| 	by mailserver (Postfix) with SMTP id 673072767C
| 	for <my at mail.address.tld>; Wed, 11 Jul 2007 13:36:07 +0200 (CEST)
| Message-Id: <20070711113611.673072767C at mailserver>
| Date: Wed, 11 Jul 2007 13:36:07 +0200 (CEST)
| From: MAILER-DAEMON
| To: undisclosed-recipients:;

It seems that postfix changes the return-path, and I dont see why it
would do something like that.

The bounce is not a bounce anymore, and if a user fetches the mail
with e.g. fetchmail, and it cannot be delivered, then the bounce
will be bounced, to MAILER-DAEMON ..

My master.cf entry looks like this:

dovecot   unix  -       n       n       -       -       pipe
 flags=DRhu user=atmail:atmail argv=/usr/local/dovecot/libexec/dovecot/deliver -d ${recipient}

If I add null_sender= , then that resolves it:

dovecot   unix  -       n       n       -       -       pipe
 flags=DRhu user=atmail:atmail null_sender= argv=/usr/local/dovecot/libexec/dovecot/deliver -d ${recipient}


What do other postfix/dovecot-users do? Will this change break
anything? I cannot see why empty null_sender isn't default .. so I'm
wondering if there is something I've missed.

Should we update the examples on http://wiki.dovecot.org/LDA/Postfix
to include empty null_sender?

-- 
Erland Nylend